Friction welding apparatus

ABSTRACT

In a friction welding machine one workpiece chuck is urged by a ram or rams towards a second workpiece chuck which is rotatable. The second chuck is supported in bearings with freedom for limited axial displacement under axial thrusts transmitted to it from the ram or rams through the workpieces and is supported against the thrusts by a hydrostatic thrust bearing.

United States Patent .lenkinson et al.

[ 1 Jan. 18, 1972 [54] FRICTION WELDING APPARATUS {72] Inventors: BrianE. .lenkinson, Barkston, near Grantham; Geoffrey W. Watson,

Grantham; Peter B. Foister, Melton Mow- -bray, all of England [73]Assignee: Steelweld Limited, Grantham, England [22] Filed: Jan. 30, 1969[21] Appl. No.: 795,306

[30] Foreign Application Priority Data Feb. 5, 1968 Great Britain..5,666/68 [52] U.S. Cl ..228/2, 29/4703, 308/9 [51] Int. Cl l ..B23k27/00 [58] Field of Search ..228/2; 29/4703; 156/73; 308/9 [56]References Cited UNITED STATES PATENTS Calton et al ..29/497.5 X

3,516,591 Gage ..228/2 3,412,916 11/1968 Dunlap et al. ..228/2 3,380,6414/1968 Deemie et al ..228/2 3,337,108 8/1967 Taylor ..228/2 PrimaryExaminer-John F. Campbell Assistant Examiner-R, J. Craig AttorneyLarson,Taylor and Hinds, Walter Gillis, Marvin Petry, Thomas P. Sarro and RossF. Hunt, Jr

[5 7] ABSTRACT In a friction welding machine one workpiece chuck isurged by a ram or rams towards a second workpiece chuck which isrotatable. The second chuck is supported in bearings with freedom forlimited axial displacement under axial thrusts transmitted to it fromthe ram or rams through the workpieces and is supported against thethrusts by a hydrostatic thrust bearing.

5 Claims, 2 Drawing Figures FRICTION WELDINGAPPAIIATUS DESCRIPTIONrelative rotation of the contacting workpieces to cause friction.

heating, and the chucks'beingrelatively. axiallydisplaceable by a ram orrams to apply the required. axialaweldingloads between the frictionallyheated workpieces.

I-ligh' relative rotationalspeeds and .widely varying, .andultimatelyhigh, axial loads are necessary to produce a good fric tion weld. Theaxial load is usually low initially, is increased during the frictionheating stage up to weldingandis increased further during the finalforging stage after relative rotation has been stopped-Axial pressuresof the order of ZOtons/in. are usual during this last stage.

As a consequence of the loads employed, design difficulties occurparticularly in regard to supporting the workpiece chucks throughrolling bearings.

These difficulties are avoided by thepresent invention, according towhich in a friction welder of the class specified. one chuck is moved bythe ram or rams and the second chuck is supported in bearings so as tohave freedom forrlimited axial displacement under the axial thrust ofthe ram or. rams through the workpieces and is supported against suchaxial thrust by a hydrostatic thrust bearing.

For example, in a friction welder in whichone chuck is displaced axiallyby the ram or rams to produce theaxial welding loads and thesecond isrotatively driven,.the rotating chuck and parts rotating with it may belocated axially by a hydrostatic bearing arranged so that widevariations in the axial load are accommodated by small displacements ofthese parts". The one chuck, which is nonrotating, may conveniently becarried by the piston of an hydraulic ram orrams', lnithis case, thesame hydraulic'high-pressure supply can beused for operating the ram andfor feeding hydraulic fluid to-the-hydrostatie thrust bearing. I

The accompanying drawings illustrate diagrammatically one form offriction welder of this inventionland some features utilizable with thewelder, in which drawings:

FIG. 1 illustrates the welder, and

FIG. 2is a section on theline A--A of FIG. 1.

The welder comprises, FIGS. 1 and 2, a nonrotating chuck which isaxially movable by being connected totthe piston 12 of an hydraulic ram13 for applying the welding loads: The ram is supplied withhigh-pressure liquid for its operation from pipeline 30.

The welding apparatus also has a rotatable chuck 11- carried on anaxial-driven shaft 14 which extends through a bearing arrangement 15.

The bearing arrangement 15 comprises a housing 16 .withaxiallyspacedjournal bearings 17 in end walls l8supporting the shaft 14 with freedomfor axial displacement, and is also such as to support the shaft withlimited movement against the high and widely varying axial loadstransmitted to thechuck 11 through the workpieces during welding.

Thrust loads are taken in the bearing arrangement 15 as follows. Aninternal annular diaphragm 19 is fixed within the casing 16 between twochambers 20, 2l,and the diaphragm 19 has in it a gallery 22communicating with'pipeline 30 through a pressure liquid supply port23.The diaphragm 19 also has axial drillings 24 leading from the gallery22 to recessing 25 which may be an annular channel, or'series of pocketsangularly spaced around the annulus, in-the end surfacefacing chamber 21and thus facing axiallytowards the chuck 10.

The shaft 14 carries an annular collar 26, one face 27 of 70 which isclose to but spaced fromthe surface containingthe recessing 25, the face27 extending radially-inwardly and outwardly beyond the recessing 25 soas to-leaveaxially: narrow outlets such as'small leakage;.gaps 35.Drillings 28 lead from the inner'limit of face 27 to the chamber 21.

' A conduit 29 leads from chamber 21 to a drain tank. ln operation,-thepressure liquidleaks from the channel, or

* .pockets, 25 radially through'the leakage gaps and this leakage flowcreates a drop in fluid pressure with this arrange- .ment there is thusa resultantload acting towards the left in .the drawingagainst anythrust load transmitted from piston 12 throughthe workpieces to theshaft 14. If this thrust load on piston 12 increases, the shaft 14moves-axially a small amount to the right so that the leakage gaps 35decrease so increasing the pressure difference across, andfluidload on,the collar 26. Conversely, if the thrust load on piston 12 decreases theshaft 14 moves a small amount to the left to increase the size of gaps35 and decreasethe pressure difference. As noted, the .extent of axialmovement of the shaft 14 to accommodate large wthrust load changes issmall. The movement is .made even smaller by the fact that the samepressure supply is used for I the thrust bearing as for. the ram 13.

'- We claim:

1. Friction welding apparatus of theclass comprising a pair of chucks inwhich the workpieces to'b'e joined are held, the

. chucks .being relatively axially displac'eable by an hydraulic -ram tourge workpieces held in the' chucks into contact and the chucks beingrelatively rotatable to cause friction. heating of the contactingworkpieces, characterized in that one chuck is connected to be displacedaxially by the ram to produce the axial welding loads and the secondchuck is rotatively driven,

there being a hydrostatic bearing supporting the second chuck and otherrotating parts against axial loads transmitted thereto from saidhydraulic ram, said hydrostatic bearing including a high-pressure spaceand a low-pressure space interconnected 'by clearances, and means forvarying the size of said clearances in the axial direction in responseto variations of the welding load applied by the'rarn such that anincrease in the welding load reduces thesize of the clearances, thusincreasing the pressure of the hydrostatic bearing, and a decrease inthe welding load causes the size of the clearances to increase, thusdecreasing the pressure of the hydrostatic bearing, and there being ahigh-pressure liquid supply and a common connection from said supply tosaid hydraulic ram and to said high-pressure spaceof the hydrostaticbearing.

2. Friction welding apparatus according to claim 1, comprising a shaftrotatively drivingthe second chuck, the hydrostatic thrust bearing forthe second chuck comprising acasing through which the shaft extends, thecasing having a diaphragm'with recessing facing axially towards the saidone chuck, an annular collar connected to move axially with the shaftand having a radial face close t'oand extending radially inwardly andoutwardly beyond the recessing, the high-pressure liquid supply beingconnected tothe recessing and there being a drain from the casing, therebeing a leakage path for flow of pressure fluid from the recessing pastthe face to-the drain thereby creating an hydraulic thrust-opposing loadon the collar.

3. Friction welding apparatus according to claim 2, said recessing beingan annular channel.

4. Friction welding apparatus according to claim 2, said accessing beingan annular arrangement of pockets.

5. Friction welding apparatus of the class comprising a pair of chucksin'which the workpieces to be joined are held; support means comprisinga' ram having an axially displaceable nonrotating ram piston, one ofsaid pair of chucks being vvmounted for axial displacement on saidpiston, a bearing arvrangement including a hydrostatic journal bearingmeans and a hydrostatic thrust bearing means; and a driven shaftrotatively mounted in said bearing arrangement, the second of said pairof chucks being mounted on said shaft; said hydrostatic thrust bearingmeans including a casing, a diaphragm fixedly mounted in said casing andencircling said shaft, a collar fixed on said shaft, said diaphragm andsaid collar being axially spaced and having cooperating axially facingsurfaces defining between them a high-pressure space-with radiallyextending "axially narrow outlets from said high-pressure space to alowpressure space within saidcasing; the size of saidoutlets and hencealso the pressure of the hydrostatic bearing varying in response tosmall axial movements of the ram as the pressure applied to the ram, andhence the thrust applied by the ram varies, and a high-pressure liquidsource and a common supply connection from said source to said ram andto said high-pressure space. 5

i I! i i

1. Friction welding apparatus of the class comprising a pair of chucksin which the workpieces to be joined are held, the chucks beingrelatively axially displaceable by an hydraulic ram to urge workpiecesheld in the chucks into contact and the chucks being relativelyrotatable to cause friction heating of the contacting workpieces,characterized in that one chuck is connected to be displaced axially bythe ram to produce the axial welding loads and the second chuck isrotatively driven, there being a hydrostatic bearing supporting thesecond chuck and other rotating parts against axial loads transmittedthereto from said hydraulic ram, said hydrostatic bearing including ahigh-pressure space and a low-pressure space interconnected byclearances, and means for varying the size of said clearances in theaxial direction in response to variations of the welding load applied bythe ram such that an increase in the welding load reduces the size ofthe clearances, thus increasing the pressure of the hydrostatic bearing,and a decrease in the welding load causes the size of the clearances toincrease, thus decreasing the pressure of the hydrostatic bearing, andthere being a highpressure liquid supply and a common connection fromsaid supply to said hydraulic ram and to said high-pressure space of thehydrostatic bearing.
 2. Friction welding apparatus according to claim 1,comprising a shaft rotatively driving the second chuck, the hydrostaticthrust bearing for the second chuck comprising a casing through whichthe shaft extends, the casing having a diaphragm with recessing facingaxially towards the said one chuck, an annular collar connected to moveaxially with the shaft and having a radial face close to anD extendingradially inwardly and outwardly beyond the recessing, the high-pressureliquid supply being connected to the recessing and there being a drainfrom the casing, there being a leakage path for flow of pressure fluidfrom the recessing past the face to the drain thereby creating anhydraulic thrust-opposing load on the collar.
 3. Friction weldingapparatus according to claim 2, said recessing being an annular channel.4. Friction welding apparatus according to claim 2, said recessing beingan annular arrangement of pockets.
 5. Friction welding apparatus of theclass comprising a pair of chucks in which the workpieces to be joinedare held; support means comprising a ram having an axially displaceablenonrotating ram piston, one of said pair of chucks being mounted foraxial displacement on said piston; a bearing arrangement including ahydrostatic journal bearing means and a hydrostatic thrust bearingmeans; and a driven shaft rotatively mounted in said bearingarrangement, the second of said pair of chucks being mounted on saidshaft; said hydrostatic thrust bearing means including a casing, adiaphragm fixedly mounted in said casing and encircling said shaft, acollar fixed on said shaft, said diaphragm and said collar being axiallyspaced and having cooperating axially facing surfaces defining betweenthem a high-pressure space with radially extending axially narrowoutlets from said high-pressure space to a low-pressure space withinsaid casing; the size of said outlets and hence also the pressure of thehydrostatic bearing varying in response to small axial movements of theram as the pressure applied to the ram, and hence the thrust applied bythe ram varies, and a high-pressure liquid source and a common supplyconnection from said source to said ram and to said high-pressure space.